Split-cycle internal combustion engines are known in the art. One example of a split-cycle combustion engine can be found in International Patent Application Pub. No. WO 2003/008785, which is assigned to the Scuderi Group. This application is concerned with offsets to optimize the compression stroke in a split-cycle engine, and describes operation on a single, spark-ignited fuel.
Additionally, internal combustion engines operating with more than one fuel are known. Certain engines use two or more fuels having different reactivities. One example of such an engine can be seen in U.S. Patent Application Pub. No. 2011/0192367, which was published on Aug. 11, 2011 to Reitz et al. (hereafter, “Reitz”). Reitz describes a compression ignition engine that uses two or more fuel charges having two or more reactivities to control the timing and duration of combustion. However, as Reitz describes, engine power output and emissions depend on the reactivity of the fuels, temperature, equivalence ratios and many other variables, which in real-world engine applications cannot be fully controlled. For example, fuel quality may change by season or region, and the temperature of incoming air to the engine depends on the climatic conditions in which the engine operates. Moreover, other parameters such as altitude and humidity can have an appreciable effect on engine operation.
Engine combustion systems that use stratified fuel/air regions in the cylinder having different reactivities, such as that described by Reitz, are known to work relatively well at low engine loads, where the various strata within the cylinder have a chance to fully develop, but the technology is not proven to work for higher engine loads, where the fuel amounts within the cylinder are increased and/or the incoming air to the cylinder is accelerated. Thus, the combustion system of Reitz may not be suitable for certain engine applications where higher loads are required.